lightning/common/json.c

/* JSON core and helpers */
#include "json.h"
#include <assert.h>
#include <bitcoin/pubkey.h>
#include <ccan/build_assert/build_assert.h>
#include <ccan/mem/mem.h>
#include <ccan/str/hex/hex.h>
#include <ccan/tal/str/str.h>
#include <common/utils.h>
#include <errno.h>
#include <inttypes.h>
#include <stdarg.h>
#include <stdio.h>
#include <string.h>

const char *json_tok_full(const char *buffer, const jsmntok_t *t)
{
	if (t->type == JSMN_STRING)
		return buffer + t->start - 1;
	return buffer + t->start;
}

/* Include " if it's a string. */
int json_tok_full_len(const jsmntok_t *t)
{
	if (t->type == JSMN_STRING)
		return t->end - t->start + 2;
	return t->end - t->start;
}

bool json_tok_streq(const char *buffer, const jsmntok_t *tok, const char *str)
{
	if (tok->type != JSMN_STRING)
		return false;
	if (tok->end - tok->start != strlen(str))
		return false;
	return strncmp(buffer + tok->start, str, tok->end - tok->start) == 0;
}

char *json_strdup(const tal_t *ctx, const char *buffer, const jsmntok_t *tok)
{
	return tal_strndup(ctx, buffer + tok->start, tok->end - tok->start);
}

bool json_to_u64(const char *buffer, const jsmntok_t *tok,
		  uint64_t *num)
{
	char *end;
	unsigned long long l;

	l = strtoull(buffer + tok->start, &end, 0);
	if (end != buffer + tok->end)
		return false;

	BUILD_ASSERT(sizeof(l) >= sizeof(*num));
	*num = l;

	/* Check for overflow */
	if (l == ULLONG_MAX && errno == ERANGE)
		return false;

	if (*num != l)
		return false;

	return true;
}

bool json_to_double(const char *buffer, const jsmntok_t *tok, double *num)
{
	char *end;

	*num = strtod(buffer + tok->start, &end);
	if (end != buffer + tok->end)
		return false;
	return true;
}

bool json_to_number(const char *buffer, const jsmntok_t *tok,
		    unsigned int *num)
{
	uint64_t u64;

	if (!json_to_u64(buffer, tok, &u64))
		return false;
	*num = u64;

	/* Just in case it doesn't fit. */
	if (*num != u64)
		return false;
	return true;
}

bool json_to_int(const char *buffer, const jsmntok_t *tok, int *num)
{
	char *end;
	long l;

	l = strtol(buffer + tok->start, &end, 0);
	if (end != buffer + tok->end)
		return false;

	BUILD_ASSERT(sizeof(l) >= sizeof(*num));
	*num = l;

	/* Check for overflow/underflow */
	if ((l == LONG_MAX || l == LONG_MIN) && errno == ERANGE)
		return false;

	/* Check for truncation */
	if (*num != l)
		return false;

	return true;
}

bool json_to_bool(const char *buffer, const jsmntok_t *tok, bool *b)
{
	if (tok->type != JSMN_PRIMITIVE)
		return false;
	if (memeqstr(buffer + tok->start, tok->end - tok->start, "true")) {
		*b = true;
		return true;
	}
	if (memeqstr(buffer + tok->start, tok->end - tok->start, "false")) {
		*b = false;
		return true;
	}
	return false;
}

bool json_tok_is_num(const char *buffer, const jsmntok_t *tok)
{
	if (tok->type != JSMN_PRIMITIVE)
		return false;

	for (int i = tok->start; i < tok->end; i++)
		if (!cisdigit(buffer[i]))
			return false;
	return true;
}

bool json_tok_is_null(const char *buffer, const jsmntok_t *tok)
{
	if (tok->type != JSMN_PRIMITIVE)
		return false;
	return buffer[tok->start] == 'n';
}

const jsmntok_t *json_next(const jsmntok_t *tok)
{
	const jsmntok_t *t;
	size_t i;

	for (t = tok + 1, i = 0; i < tok->size; i++)
		t = json_next(t);

	return t;
}

const jsmntok_t *json_get_member(const char *buffer, const jsmntok_t tok[],
				 const char *label)
{
	const jsmntok_t *t, *end;

	if (tok->type != JSMN_OBJECT)
		return NULL;

	end = json_next(tok);
	for (t = tok + 1; t < end; t = json_next(t+1))
		if (json_tok_streq(buffer, t, label))
			return t + 1;

	return NULL;
}

const jsmntok_t *json_get_arr(const jsmntok_t tok[], size_t index)
{
	const jsmntok_t *t, *end;

	if (tok->type != JSMN_ARRAY)
		return NULL;

	end = json_next(tok);
	for (t = tok + 1; t < end; t = json_next(t)) {
		if (index == 0)
			return t;
		index--;
	}

	return NULL;
}

jsmntok_t *json_parse_input(const tal_t *ctx,
			    const char *input, int len, bool *valid)
{
	jsmn_parser parser;
	jsmntok_t *toks;
	int ret;

	toks = tal_arr(ctx, jsmntok_t, 10);
	toks[0].type = JSMN_UNDEFINED;

	jsmn_init(&parser);
again:
	ret = jsmn_parse(&parser, input, len, toks, tal_count(toks) - 1);

	switch (ret) {
	case JSMN_ERROR_INVAL:
		*valid = false;
		return tal_free(toks);
	case JSMN_ERROR_NOMEM:
		tal_resize(&toks, tal_count(toks) * 2);
		goto again;
	}

	/* Check whether we read at least one full root element, i.e., root
	 * element has its end set. */
	if (toks[0].type == JSMN_UNDEFINED || toks[0].end == -1) {
		*valid = true;
		return tal_free(toks);
	}

	/* If we read a partial element at the end of the stream we'll get a
	 * ret=JSMN_ERROR_PART, but due to the previous check we know we read at
	 * least one full element, so count tokens that are part of this root
	 * element. */
	ret = json_next(toks) - toks;

	/* Cut to length and return. */
	*valid = true;
	tal_resize(&toks, ret + 1);
	/* Make sure last one is always referenceable. */
	toks[ret].type = -1;
	toks[ret].start = toks[ret].end = toks[ret].size = 0;

	return toks;
}

const char *jsmntype_to_string(jsmntype_t t)
{
	switch (t) {
		case JSMN_UNDEFINED :
			return "UNDEFINED";
		case JSMN_OBJECT :
			return "OBJECT";
		case JSMN_ARRAY :
			return "ARRAY";
		case JSMN_STRING :
			return "STRING";
		case JSMN_PRIMITIVE :
			return "PRIMITIVE";
	}
	return "INVALID";
}

void json_tok_print(const char *buffer, const jsmntok_t *tok)
{
	const jsmntok_t *first = tok;
	const jsmntok_t *last = json_next(tok);
	printf("size: %d, count: %td\n", tok->size, last - first);
	while (first != last) {
		printf("%td. %.*s, %s\n", first - tok,
		        first->end - first->start, buffer + first->start,
			jsmntype_to_string(first->type));
		first++;
	}
	printf("\n");
}

jsmntok_t *json_tok_copy(const tal_t *ctx, const jsmntok_t *tok)
{
	return tal_dup_arr(ctx, jsmntok_t, tok, json_next(tok) - tok, 0);
}

void json_tok_remove(jsmntok_t **tokens, jsmntok_t *tok, size_t num)
{
	assert(*tokens);
	assert((*tokens)->type == JSMN_ARRAY || (*tokens)->type == JSMN_OBJECT);
	const jsmntok_t *src = tok;
	const jsmntok_t *end = json_next(*tokens);
	jsmntok_t *dest = tok;
	int remove_count;

	for (int i = 0; i < num; i++)
		src = json_next(src);

	remove_count = src - tok;

	memmove(dest, src, sizeof(jsmntok_t) * (end - src));

	tal_resize(tokens, tal_count(*tokens) - remove_count);
	(*tokens)->size -= num;
}

const jsmntok_t *json_delve(const char *buffer,
			    const jsmntok_t *tok,
			    const char *guide)
{
       while (*guide) {
               const char *key;
               size_t len = strcspn(guide+1, ".[]");

               key = tal_strndup(tmpctx, guide+1, len);
               switch (guide[0]) {
               case '.':
                       if (tok->type != JSMN_OBJECT)
                               return NULL;
                       tok = json_get_member(buffer, tok, key);
                       if (!tok)
                               return NULL;
                       break;
               case '[':
                       if (tok->type != JSMN_ARRAY)
                               return NULL;
                       tok = json_get_arr(tok, atol(key));
                       if (!tok)
                               return NULL;
                       /* Must be terminated */
                       assert(guide[1+strlen(key)] == ']');
                       len++;
                       break;
               default:
                       abort();
               }
               guide += len + 1;
       }

       return tok;
}